Carboxy vinyl polymer and partially hydrolyzed polyacrylamide mobility control agent and process

ABSTRACT

Carboxy vinyl polymer (e.g., Carbopol 961) when dissolved with partially hydrolyzed polyacrylamide (e.g., Dow 700) increases screen factor and provides enhanced supplemented recovery of oil.

EJ111166 States Patent Norton et a1.

[ July 23, 1974 1 CARBOXY VINYL POLYMER AND 3,308,885 3/1967 Sandiford 166/305 R x PARTIALLY HYDRQLYZED 3,402,137 9/1968 Fischer et a1. 166/305 R 3,543,855 12/1970 Blatz et al 166/275 X POLYACRYLAMIDE MOBILHTY CONTROL 3,634,305 l/l972 Johnson et a1 166/274 X AGENT AND PROCESS 3,679,000 7/1972 Kaufman 166/275 x 75 Inventors; Charles J. Norton; David 0 Falk, 3,684,014 8/1972 Norton ct a1. 166/275 both of Denver Colo 3,687,199 8/1972 Jennings 166/274 [73] Assignee: Marathon Oil Company, Findlay,

Ohio Primary Examiner-Stephen J. Novosad Assistant Examiner-Jack E. Ebel [22] Flled: 1972 Attorney, Agent, or Firm.1oseph C. Herring; Richard [21] APPL 238,143 C. Willson, Jr.; Jack L. Hummel [52] 11.8. C1 166/305 R, 166/275, 252/855 D 51 Intel E211) 43/116 [57] ABSTRACT [58] Fleld of Search 166/273-275, Carboxy vinyl p y c p 9 1 when 166/305 252/855 89 solved with partially hydrolyzed polyacrylamide (e.g.,

Dow 700) increases screen factor and provides en- [56] References C'ted hanced supplemented recovery of oil.

UNITED STATES PATENTS 2,798,053 7/1957 Brown .1 252/89 X 11 Claims, 2 Drawing Figures E O U E 2 1.1.1 lL! m U 0') O CARBOXY VINYL 200 POLYACRY LAM IDE CONCENTRATION PPM PATENTEU M2319M SCREEN FACTOR BEE-5,088

O CARBOXY VlNYL 200 POLYACRYLAMIDE CONCENTRATION Fig. 2

PPM

PERCENT RESIDUAL OIL RECOVERY O POLYACRYLAMIDE 50 I00 CARBOXY VINYL 5O 0 PERCENT THICKENER CONTROL AGENT AND PROCESS CROSS REFERENCES TO RELATED APPLICATIONS The following cases relate to the same general field as that of the present invention: U.S. Pat. No. 3,507,331; U.S. Pat. No. 3,467,187; S/N 74,336 filed Sept. 22, 1970 now U.S. Pat. No. 3,677,344; S/N 76,140 filed Sept. 28, 1970 now U.S. Pat. No. 3,724,545; I S/N 67,726 filed Aug. 28, 1970 now U.S. Pat. No. 3,670,820; S/N 79,591 filed Oct. 9, 1970 now U.S. Pat. No. 3,692,113; S/N 85,064 filed Oct. 29, 1970 now U.S. Pat. No. 3,684,014; S/N 126,731 filed Mar. 22, 1971; S/N 133,060 filed Apr. 12, 1971; S/N 140,931 filed May 6, 1971; S/N 209,479 filed Nov. 26, 1971;

.S/N 238,142 filed Mar.27, 1972;

S/N 220,910 filed Jan. 26, 1972; and

BACKGROUND OF THE INVENTION 1; Field of the Invention The present invention relates primarily to wells classified in Class 166 of the U.S. Pat. Office, and more particularly to production of earth fluid by driving fluid classified in Class 166 subclass 252. f

2. Description of the Prior Art Water flooding with mobility-reducing agents, e.g., high molecular weight partially hydrolyzed polyacrylamides, such as Dow Chemical Company 700, has been successfully used to recover increased amounts of oil in secondary recovery methods. U.S. Pat. No. 2,827,964, teaches secondary recovery of petroleum fromsubterranean formations using water-soluble partially hydrolyzed acrylamide polymer. U.S. Patent application Ser. No. 76,140,filed Sept. 28, 1970 (Docket No. 690087-A-USA), copending, teaches improved mobility control of petroleum recovery by injecting at least two slugs, one containing a permeability reduction agent, e.g., partially hydrolyzed, high molecular weight polyacrylamide, and the other slug containing a fluid viscosity-increasing agent, e. g., a linear polysaccharide or other bipolymer.

Carboxy vinyl polymers (CVP), e.g., B. F. Goodrich Chemical Companys Carbopo1, (described in their Service Bulletin GC-36) have been used as viscosityincreasing agents in secondary recoveryoperations. However, the present invention embodies the discovery that a combination of two agents provides unexpected increase in-the efficiency of petroleum recovery, substantially above that which would be expected from an examination of data on the use of either of the polymers alone. The prior art discussed in the aforementioned related applications also has applicability to the general field of the present invention.

A design criterion for an optimum flooding process is to have the mobility of the displacing fluid about equal to or less than that of-the combination of the formation fluids (hydrocarbon and interstitial water) within the reservoir. This has usually been accomplished by injecting into the water flood a single agent to effect a reduction in mobility. Most commonly, this agent is a partially hydrolyzed, high molecular weight polyacrylamide.

SUMMARY OF THE INVENTION This invention relates to a method of improving mobility control of a flooding process by injecting an aqueous solution of CVP and partially hydrolyzed polyacrylamide into the oil bearing formation. The result of the injection of this aqueous solution is a substantial increase in the screen factor property and also the production of petroleum from subterranean formations.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the unexpected synergistic improvement in screen factor obtained with a thickener formu- DESCRIPTION OF THE PREFERRED EMBODIMENTS Starting Materials:

By carboxy vinyl polymer is meant herein high molecular weight polymers containing predominantly carboxy vinyl monomer units.

By partially hydrolyzed polyacrylamide is meant herein polyacrylamide which has been hydrolyzed to 0.1 to percent, more preferably to l to 45 percent, most preferably 5 to 30 percent, of theory.

Partially hydrolyzed polyacrylamide will preferably have molecular weights in the range above 0.1 X 10, preferably from 0.5 to 40 X 10 more preferably. from 1 X 10 to 15 X 10 and most preferably from 3X 10 to 10 X 10. Preferably the partially hydrolyzed polyacrylamidewill be present in amounts of from about 0.001 to about 10.0, more preferably from 0.01- to about 1.0, and most preferably from 0.02 to about 0.2 weight percent based on the weight of the total solution.

The carboxy vinyl polymer (CVP) will preferably have a molecular weight above 0.1. X 10 preferably 0.5 to about 20 X 10 more preferably from 1 to about 15 X 10 and most preferably from 3 X 10 to about 10 x 10.

Preferably, the CVP will be present in amounts from about 0.001 to about 10, more preferably from 0.01 to about 1.0, and most preferably from 0.02 to about 0.2

weight percent based on the total solution.

The solvent for the liquid solutions of the present invention are comprised of water, most preferably consist essentially of connate water, for example, Palestine line water, freshwater, or brackish water. It is preferable that the water contain less than about 300,000, more preferably less than about 10,000, and most preferably less than about 500 parts per million of dissolved solids. The resulting aqueous solution of CVP and partially bydrolyzed polyacrylamide will preferably have viscosity of from about 1.5 to about 1,000 cps, more preferably from about 5 to about 500 cps, and most preferably from 10 to about 100 cps.

While not necessary to the practice of the present invention, various other ingredients including among othmination of a preliminary secondary water-flood opera-- W tion. This condition is achieved by first saturating the .core with artificial Henry field water, then partially displacing this water with Henry field crude oil until satuers, cellulose derivatives and surfactants, e.g.,polyalkyl 5 rated with crude 1, 1), and i y f flooding aryl sulfonate and other conventional displacement vlth artlficlal Henry water to residual 1 r) and fluid additives may be added to the liquid polymer solu- Sldual Water SIatUFatIOYIS- tions. Preparation of Liquid Systems: It will generally The comparablhues of the examples employing varibe preferable to merely co-mix CVP and the partially OHS thlckeners 1n supplemented recovery operations hydrolyzed polyacrylamide and then add water while are estabhshed y P P aqx data on P9? gently stirring to promote dispersion, suspension, and limes p fi i permeabllltles l), mltlal 011 solution. Bubbling a small amount of non-reactive gas, and Wafer Saturatlons 1, 1) reSldual Oil and water e.g., natural gas, may be used to effect mild stirring. SaturaUOflS (Q1 and wr) after preparatlon Simulated The ingredients will preferably be mixed at ambient water flood yp Henry field plant water. and temperature, more preferably from 0C. to about similar efficiencies of water flood recovery (Eff). 100C, and most preferably from 209C. to about C, In all experiments supplemental floods a 0.03 PY slug If desired, a mixing operation can be employed in one of a petroleum sulfonate (FF-5 W35 Pushed In h or more full-type mixers or mixing tees so long as the secondary flood ng operation by up to about 1 PV of proportions of the ingredients are properly measured the particular thlckened water. In each example the nand thoroughly mixed. Bacteriocides and antioxidants 2 jection of thickened water was continued to the point can be advantageously added to preserve the viscosity at which no additional 011 was recovered. The data are of the solution. Screen Factor: Aqueous solutions of summarized n Table l, the t column of wh1ch l sts CVP and partially hydrolyzed polyacrylamide are prethe percent or] recovery based on res dual oil remammg pared by weighing both solids into a bottle, adding deafter the prel m nary water flood. ionized water, stirring slowly with a'magnetic bar for 25 The synerg1st1c effect of thickened water prepared several hours until visibly dissolved, and then allowing from m1xed compositionsof partially hydrolyzed polyitan r 92 s. .aLTs a @y sr ea..fastq iiis. f la 1.efl.. ll? ael tee9 1 1?- Table 1 SUMMARY OF THICKENED WATER SUPPLEMENTED RECOVERIES' T I H 2 .h v I ota Exampv Poros Permea- .Thickened Water ple Run bility Recoverv Numb. lr md in g g M h i i 01 or Wr *Jf2 se 1 .PQ @929 1 06118 1038 20.2 62 .0 63.8 36.2 38.4 61.6 39.8 500 ppm partially hydrolyzed polyacrlamide 0.957 60.8 2 07101 1031 20.0 557.2 62.3 37.7 38.9 61.1 37.6 500 ppm partially hydrolyzed polyacrlamide 0.968 60.9 3 09140 1083 21.0 680.1 63.9 36.1 40.4 59.6 36.8 250 ppm partially hydrolyzed polyacrlamide 1.02 53.9 250 ppm carboxyvinyl polymer 4 09137 1092 21.2 780.4 62.5 37.5 36.3 63.7 41.9 500 ppm carboxy vinyl 1.02 39.5

polymer 3 in. diameter by 4 ft. long Berea sandstone (fired at 825F.) was first saturated with artificial Henry plant brine (containing ll,000 ppm C1. 6500 ppm Na. 276 ppm Ca, 167 ppm Mg) and Henry Crude to an initial oil saturation (0,) and initial water saturation (W0; the core was subsequent] flooded to residual saturation (O, and W,) and then flood at rates of 1.9 to 3.7 ft/ ay with 0.03 P V of FF-56l slug (petroleum sulfonate slug) followed by up to 1 pore volume of synthetic Palestine Water" (containing 400 ppm NaCl and ppm CaCl,) and the additional crude recovered and calculated as percent of residual oil in the core before this final flood.

done according to Society of Petroleum. Engineers Paper No. 2867, and the test results are summarized in FIG. 1.

Carbopol CVP 961 was used in applicants Examples l-lV. Examples:

EXAMPLES I-lV Examples 1 through IV are run under identical condi tions. 1

MODIFICATIONS or THE INVENTION leading edge of the displacement slug and gradually 7 using a higher and higher percentage of partially hydrolyzed polyacrylamides, to provide a slug which is rich at its leading edge where depletion is most likely to occur. lnitial viscosity of the slug may be the same at all points throughout the slug or may be itself gradually decreased until it approaches that of the drive fluid which displaces the slug through the formation.

What is claimed is:

1. A process for the displacement of oil in an oilbearing formation comprising injecting into said formation an aqueous solution comprised of about 0.001 to about percent by weight of a water-soluble partially hydrolyzed polyacrylamide and about 0.001 to about 10 weight percent water-soluble carboxy vinyl polymer based on the weight of the total solution.

2. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide polymer has a molecular weight above 100,000 prior to comixing with said carboxy vinyl polymer.

3. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide has a molecular weig-- tially hydrolyzed polymer is present in a concentration of frornabout 0.01 to about 1.0 percent by weight based on the weight of the total solution.

5. A process according to claim 1 wherein the aque ous solution is characterized by a viscosity of from about 1.5 to about 1,000 centipoises.

6. A process according to claim 5 wherein the aqueous solution is characterized by a viscosity of from about 5 to about 500 centipoises.

7. A process according to claim 5 wherein the aqueous solution is characterized by a viscosity of from about 10 to about 100 centipoises.

8. Processes according to claim 1 wherein the carboxy vinyl polymer has a molecular weight above 100,000.

9. Processes according to claim 1 wherein the carboxy vinyl polymer has a molecular weight in the range of from about 500,000 to about 20,000,000.

10. Processes according to claim 1 wherein the carboxy vinyl polymer is present in a concentration of from about 0.01 to about 1.0 percent by weight based on the weight of the total solution.

11. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide polymer is hydrolyzed from about 0.1 to about percent. 

2. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide polymer has a molecular weight above 100,000 prior to comixing with said carboxy vinyl polymer.
 3. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide has a molecular weight of from about 500,000 to about 20,000,000 and is hydrolyzed to from about 0.1 to about 70 percent of theory.
 4. Processes according to claim 1 wherein the partially hydrolyzed polymer is present in a concentration of from about 0.01 to about 1.0 percent by weight based on the weight of the total solution.
 5. A process according to claim 1 wherein the aqueous solution is characterized by a viscosity of from about 1.5 to about 1,000 centipoises.
 6. A process according to claim 5 wherein the aqueous solution is characterized by a viscosity of from about 5 to about 500 centipoises.
 7. A process according to claim 5 wherein the aqueous solution is characterized by a viscosity of from about 10 to about 100 centipoises.
 8. Processes according to claim 1 wherein the carboxy vinyl polymer has a molecular weight above 100,000.
 9. Processes according to claim 1 wherein the carboxy vinyl polymer has a molecular weight in the range of from about 500,000 to about 20,000,000.
 10. Processes according to claim 1 wherein the carboxy vinyl polymer is present in a concentration of from about 0.01 to about 1.0 percent by weight based on the weight of the total solution.
 11. Processes according to claim 1 wherein the partially hydrolyzed polyacrylamide polymer is hydrolyzed from about 0.1 to about 70 percent. 